Corrosion in Tinplate Cans Used for Food Storage, Part 2: Characterization and Corrosion Phenomena in BPA-NI Coated Cans

Corrosion phenomena associated with tinplate cans were investigated with aqueous solutions of different compounds commonly found in canned tomato products. After only a few weeks of storage at 49 degrees C, cans lined with a coating with bisphenol A (BPA) not intentionally added (BPA-NI) displayed degradation of the coating. Storage of solutions containing chloride, nitrate, and thiosulfate ions in the BPA-NI coated cans resulted in extensive formation of blisters. Additionally, headspace blackening, which is sometimes found in packaged protein-containing foods, was also observed. Volatile sulfur-containing compounds produced during the sterilization process might be the origin of headspace blackening. In this study, the corrosion of tinplate cans exposed to different solutions at 49 degrees C for varying storage times was studied via optical microscopy, optical profilometry, x-ray diffraction, scanning electron microscopy, and Raman spectroscopy. The results showed a strong correlation between the presence of cysteine, an amino acid, and/or nitrate, and the degradation of the coating. Furthermore, cysteine was found to be a source of headspace blackening.

Automated summary

This study investigated corrosion phenomena associated with tinplate cans exposed to different aqueous solutions commonly found in canned tomato products. The presence of cysteine, an amino acid, and/or nitrate were found to correlate strongly with degradation of the coating, while storage of chloride, nitrate, and thiosulfate ions in cans with bisphenol A (BPA) not intentionally added (BPA-NI) led to extensive blister formation. Additionally, volatile sulfur-containing compounds produced during sterilization may be the origin of headspace blackening in protein-containing foods.